1. Field of the Invention
This invention relates to an elastic blade for regulating the layer thickness of a toner, a method of manufacturing the same and a developing device using the elastic blade.
2. Related Background Art
Heretofore, in the developing device of an image forming apparatus such as an electrophotographic apparatus, the thickness of a toner layer on a developing sleep carrying a toner thereon has been regulated by an elastic blade and triboelectricity has been imparted to the toner by friction.
A blade made of rubber is used as such elastic blade.
However, this rubber blade, when used for a long period, has caused a variation with time (plasticity deformation) in its elastic material and has suffered from a problem in durability.
So, there has been proposed a developing device utilizing, as a blade for regulating the quantity of developer, a blade of two or more layers comprised of an elastic layer for regulating the amount of charge of a developer and a support layer for regulating pressure adhesively secured to the elastic layer.
However, the support layer of this blade of two-layer construction is thin and elongate and therefore gives rise to warp.
For this reason, this blade is affected by the warp of the support layer and it is difficult to obtain uniform contact pressure in the lengthwise direction of a developing sleeve and therefore, it would occur to mind to form a blade for regulating the quantity of developer which is high in flatness. If the flatness of the blade for regulating the quantity of developer is thus made high, the toner could be uniformly regulated and charged in the whole widthwise direction on the sleeve and the pressure regulation by space saving, low cost and highly accurate setting will not be required.
For this purpose, however, the flatness of the support layer must not be made high and the manufacturing process becomes complicated and difficult.
It is an object of the present invention to provide an elastic blade which is high in flatness and a method of manufacturing the same.
It is another object of the present invention to provide an elastic blade having a base layer and an elastic layer provided on the convex surface side of said base layer.
It is still another object of the present invention to provide a method of manufacturing an elastic blade having the step of forming a curved base layer, and the step of thermally securing and shaping an elastic layer on the convex surface side of said base layer.
It is yet still another object of the present invention to provide a developing device having a toner carrying member for carrying a toner thereon, and a regulating blade for regulating the layer thickness of the toner on said toner carrying member, said regulating blade having a base layer and an elastic layer provided on the convex surface side of said base layer, said elastic layer side being urged toward said toner carrying member.
Further objects of the present invention will become apparent from the following detailed description.